Flexible belt carrier mechanism

ABSTRACT

Rigid connectors between adjacent portions of flexible belt elements are fastened thereto in such a manner that when the belt flexes as it moves over supporting drums bending stresses are avoided at the fastenings. The flexible belt may be of segmental or continuous form. The connectors may be in the form of carrier plates employed to carry pieces to be worked upon during the movements of the connectors, or the connectors may be of a form or carry means to push unattached objects. In either case, movements may be continuous or intermittent. In cases in which the connectors are massive or carry massive parts, means are provided to prevent inertial oscillations during changes from translatory to angular movements of the connectors.

.FMLZ5, 1972 United States atent Woltjen 2,357,718 9/l944Fleckenstein.................i......74/23lC 3,394,794 7/1968Styles..................i... ........74/23lCX [54] FLEXIBLE BELT CARRIERMECHANISM [72] Inventor:

Duane W. Woltjen, Manchester, M0. Primary Examiner-Leonard H. GerinAssignee: UMC Industries, Inc., St. Louis, Mo. Atwmey K0emg SenmgerPowers & Leavm Filed: Feb. 16, 1971 ABSTRACT Appl. No.: 115,258 Rigidconnectors between adjacent portions of flexible belt elements arefastened thereto insuch a manner that when the Related US. ApplicationData belt flexes as it moves over supporting drums bending stresses areavoided at the fastenings. The flexible belt may be of seg- [62] Dlvslonof 884511 1969' mental or continuous form. The connectors may be in theform of carrier plates employed to carry pieces to be worked upon duringthe movements of the connectors, or the connectors may be of a form orcarry means to push unattached ob- JCCIS. In either case, movements maybe continuous or intermittent. In cases in which the connectors aremassive or carry massive parts, means are provided to prevent inertialoscillations during changes from translatory to angular movements of theconnectors.

References Cited 7 Claims, 14 Drawing F igure s UNITED STATES PATENTS842,611 Bell.............. .......................74/231C PATENTED JANZSi972 SHEET 1 BF 7 PATENTEU JANZS i972 SHEEI 2 BF 7 PATENTED JAN251972SHEET 3 [IF 7 PATENTED JAN 2 5 1972 SHEET 5 OF T PATENTED JAHZS 1372SHEET 7 OF 7 FLEXIBLE BELT CARRIER MECHANISM CROSS-REFERENCE TO RELATEDAPPLICATION This application is a division of my copending applicationSer. No. 884,5ll,filed Dec. 12, I969.

BACKGROUND OF THE INVENTION It has been known to mount carrier plates onendless flexible flat belts, the latter being supported on and moved bydrums (see for example US. Pat. No. 3,379,298). The manner in which theplates have heretofore been fastened to the belts, particularly when thelatter were composed of metal, was not entirely satisfactory, because ofhigh-bending stresses generated at fastenings when the belt was flexed,as during movement over a supporting drum. This shortened operating lifeof the belt. In some such devices undesirable oscillations of theconnectors may occur in approach and recessive movements to and from adrum, particularly when the plates are heavy or carry heavy workpieces.These oscillations if considerable should be avoided.

SUMMARY The invention eliminates the difficulties above referred to byforming adjacent portions of a flexible belt to include extensions whichoverlap or interdigitate in the plane of the belt so that the distalends of the extensions are spaced along the belt length. The rigidmember to be supported is then fastened to such distal ends of theextensions. Thus the fastening means between the extensions and therigid member are caused always to lie in a plane, regardless of whetherthe connector at a particular time is located in a flat reach of thebelt between drums, or in a curved portion of the belt on a drum. Whenthe fastenings are between parts which remain coplanar, rather than onepart being bent away from the other at the point of fastenings, anybending stresses at the fastenings are avoided. Oscillations which mayoccur are also prevented. According to the invention the fasteningsbetween the work-carrying connectors and flexible portions may be madequite tight for high-positional accuracy of the workpieces which theycarry; whereas heretofore if bending stresses at the fastenings were tobe avoided, looseness at the fastenings was called for, with resultinglow-positional accuracy.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a face view of a first formof belt per se made according to the invention;

FIG. 2 is an edge view sighted across line 2-2 on FIG. 1;

FIG. 3 is an enlarged cross section taken on line 33 of FIG. 1 showingdetails of certain fasteners;

FIG. 4 is a view, partly in elevation and partly in section,illustrating improved action of the belt of FIGS. 1 and 2 when supportedon a drum;

FIG. 5 is a side view of a mechanism employing the belt of FIGS. 1-4;

FIG. 6 is a fragmentary plan view of FIG. 5;

FIG. 7 is a left-end view of FIG. 5;

FIGS. 8, 9 and 10 are fragmentary side, plan and end views correspondingto the views in FIGS. 5, 6 and 7, respectively, but illustrating anotherform of the invention, parts being broken away;

FIG. 11 is an enlarged detailed cross section taken on line 11-11 ofFIG.9;

FIG. 12 is a view similar to FIG. 1 showing a third form of theinvention;

FIG. 13 is a view similar to FIG. 1 showing a fourth form of theinvention; and

FIG. 14 is a skeleton diagram illustrating certain of the basic featuresof the invention.

Corresponding reference characters indicate corresponding partsthroughout the several views of the drawings.

DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION Hereinafter the termconnector has the significance of a rigid part such as of metal whicheither carries workpieces or the like in order to carry them from placeto place, or which may be formed or have attached thereto means forengaging external objects to move them. In the first and second forms ofthe invention (FIGS. ll l) the connector forms the sole connectionbetween adjacent end portions of adjacent links; in the third form ofthe invention (FIG. 12) the connector forms the sole connection betweenadjacent end portions of a continuous belt having two ends; and in thefourth form of the invention (FIG. 13) the connector forms an auxiliaryconnec tion (not the sole connection) between adjacent portions of acontinuous and endless belt. Rigid connectors made according to theinvention may take a wide variety of forms, depending upon particularapplications. In all forms of the invention the belt material, asidefrom the connectors, is composed of thin flexible sheet material such asspring steel but may be made of other appropriate flexible sheetmaterial.

Referring to the first form of the invention illustrated in FIGS. 1-7,numeral 1 indicates a drum, shown partially in section in FIG. 4, aroundwhich is carried a belt indicated generally by the letter B. This beltis made of thin flexible links 3, composed for example and withoutlimitation of 0.016 inch (27 US. gage) cold-rolled SAE 1,074 softannealed spring steel stock. The thickness depends upon the mechanicalstrength required of a link in a given application but should not be sogreat as to interfere with the required flexibility for curvedengagement with drum 1 by bending and return to a flat condition upondisengagement.

Opposite end portions of each link 3 form extensions such as fingers 5at the right end and a tongue 7 at the left end. The links are paired inend-to-end relationships, such that the distal ends 9 of fingers 5 ofone link interdigitate with the distal ends 11 of a tongue 7 of anadjacent link, the intcrdigitation being in the plane of the belt whenflat. This interdigitation of the fingers 5 and the tongue 7 is such asto space apart their respective distal ends a distance D between lines17 and 19 in the direction of the belt length. Lines 17 and 19 areperpendicular to the center line C-C of the belt B.

Numerals 13 indicate rigid connections of rectangular form to the faces14 of which (FIG. 2) workpieces, lugs or the like may be fastened byconventional means (not shown). These are to be moved eithercontinuously or intermittently, as desired. Or, these connectors may inand of themselves be shaped on said faces 14 with projections forpushing along unconnected objects. In any event, each connector 13 isheld to the distal ends 9 of a pair of fingers 5 of one link 3 by onepair of screw fasteners 15 on line 17. Connector 13 is also held to thedistal end 11 of tongue 7 of an adjacent link 3 by another pair of likefasteners 15 on link 19. Thus the two pairs of fastenings 15 are spacedapart the distance D.

Each fastener 15 is constituted by a shoulder forming head 21 whichseats upon what is to become the inside of a link 3 (FIG. 3).Cylindrical portions 23 closely fit into coaxial holes of equaldiameters in the links 3 and in the connectors 13. The holes inconnectors 13 are shown at 25. Extending from the cylindrical portions23 are threaded shanks 27 for the acceptance of washers 29 and nuts 31.Thus it will be seen that by tightening nuts 31, rigid fastenings areaccomplished between each connector 13 and an abutted pair of the links3. It is such rigid fastenings that heretofore would have caused troublewhen connectors moved over a drum thereby engendering high-local bendingstresses at the fastenings with shortened belt life. Former provision ofplay at the fasteners to relieve the stresses was not a satisfactorysolution because of the resulting looseness of the connectors.

Referring to FIG. 4 it will be seen how bending stresses are avoidedwith tight fastenings 15. The drum 1 carries dowel pins 33 which areengageable with holes 35 formed through the links 3 in order to obtain apositive drive. The drum 1 is provided with recesses 37 for acceptingthe heads 21 of the fasteners 15. As the belt B approaches the drum, sayfrom the right as illustrated, the inside surfaces of the distal ends 9and 11 of the fingers 5 and the tongue 7 respectively remain in the flatinside plane of the belt B along its straight reach R. The rigidity ofthe connectors 13 permanently holds the inside surfaces of theinterdigitated distal portions 9 and 11 in the same plane. This state ofaffairs is maintained even after the connectors 13 take up positionsaround the drum 1 as illustrated at the left in FIG. 4. Thus. the insidesurfaces of said fastened distal ends are always coplanar and the planeis tangent to the drum surface (see planes P-P). Thus there is never anybent condition in any of the links 3 at a fastener 15 and hence thereare no bending stresses at the points of attachment between theconnectors 13 and the links 3. While tangency between planes PP and thedrum 1 is illustrated in FIG. 4 as bisecting the distance D, suchbisection is not a necessary condition. In other words the connectors 13and planes P-P may rock with respect to the drum surface so as to shiftthe points of tangency of planes P-P within the range D. However, acoplanar relationship between distal ends 9 and 11 of the fingers 5 andtongues 7 is maintained. Such rocking may occur under inertial vibrationof heavy parts carried on the connectors 13 but is ordinarily not enoughto make plane PP tangent to the drum at or near either line 17 or 19.

FIGS. 5-7 illustrate apparatus employing the belt of FIGS. 1-4. Thiscomprises side plates 39 for supporting the driving drum 1 on a driveshaft 41 and an idler drum 43 on a shaft 45. The drum 43 is constructedlike the drum 1, except that it is not power driven. Its shaft 45 may beadjusted relative to shaft 1 by conventional means (not shown) for belttensioning purposes. Drive means for the drive shaft 41 is not shownsince various drives for the purpose are known, such as continuousdrives, intermittent motion drives, etc.

In order to prevent sag in the reaches of the belt between the drums land 43, there are provided inwardly extending spaced upper tracks 47above and below the upper reach and lower track 48 below the lowerreach. Sidewise projections 49 of the connectors 13 travel between theupper tracks 47, being thus accurately held in one plane of movement inthe upper reach. Likewise, the 'proj ections 49 riding on track 48 holdthe belt in a plane in its lower reach.

Referring to FIGS. 8-11, these have been made fragmentary to provide forsufficient enlargement to show certain details. They illustratemodifications wherein primed index numbers indicate like functioningparts to those indexed with corresponding unprimed numbers in FIGS. l-7,although they may be of somewhat different shape, as hereinafter pointedout. The modified structure comprises flexible links 3' having tongues7' interdigitated with fingers 5' on adjacent links 3. These links 3'include holes 35' engaged by dowel pins 33 on a driving drum 1 havingdrive shaft 41'. An idler drum corresponding to idler drum 43 in FIGS.l-7 is not shown. In the modification (FIGS. 8-10) the connectors areindicated at 50. These connectors 50 are larger and more massive thanthe corresponding connectors 49 shown in FIGS. 5-7. This is for thepurpose of receiving heavier workpieces, such as are responsible for thegreater tendency for the connectors to oscillate as they transfer fromstraight line motion to circular motion as a drum is approached or fromcircular to straight line motion upon leaving a drum. Screw fasteners15' (like 15 shown in FIG. 3) rigidly join each connector 50 with thedistal ends of the interdigitated fingers 5 and tongue 7 of adjacentlinks 3". Each connector 50 has a substantial dimension lengthwise ofthe belt to provide for laterally extending long and short leading andtrailing extensions 51 and 53. Note in FIG. 9 that the connectors 50overlie the links 3' so that the latter for the most part arerepresented by dotted lines except for portions exposed by breaking awaypart of one connector. Note also that the members of each group offasteners 15' are located toward one end of a connector 50.

The shortextensions 51 carry rollers 55 and the long extensions 53 carryrollers 57. Side plates corresponding to side plates 39 in FIGS. 5-7 arenumbered 39' in FIGS. 8-10. In these are grooves 59 which are deepenough to accept the rollers 57 on the longer extensions 53 and also therollers 55 on the shorter extensions 51. The deep grooves 59 arestraight until they reach a point as shown at 61 in FIG. 11. Here eachcontinues as an outer circular branch 63. A shallow branch of groove 59continues as a straight portion 65 and then as an inner circular portion67. Thus as the rollers 55 approach the drum they can and do continue oninto the shallow inner circular branch groove 67; whereas the rollers57, not being able to continue into the shallow groove part 65, areswitched into the deep outer circular brancltgroove 63. The purpose ofthis arrangement is positively to hold the connectors 50 againstoscillations from tangent positions relative to drum 1', as illustratedat P in FIG. 8.

It is to be noted that the fasteners 15' between the fingers 5' and thetongues 7' are offset with respect to the center portions of theconnectors 50 which accounts for the apparently unsymmetrical positionsassumed by the connectors 50 relative to drum 1' (FIG. 8). On the otherhand, the absence of bending stresses at the fasteners 15 betweenconnectors 50 and the distal ends of fingers S and 7' are the same as inthe case of the corresponding parts 13, 5 and 7 of FIGS. I-7. Thedifference is that no oscillations of connectors 50 can occur on thedrum 1 The distance D is shown on FIGS. 8-10.

In the operation of the FIGS. 8-11 form of the invention the rollers 55and 57 follow the deep groove 59 in the reaches of the belt betweendrums. This carries the links 3' in a plane until a drum such as l isreached. At this point rollers 55 continue into the inner circulargroove 67 whereas the outer rol- [era 57 are switched into the outercircular groove 63. This holds the connectors 50 in the tangentpositions P shown in FIG. 8.

Referring to FIG. 12, it shows a belt composed, not of a plurality oflinks as in FIGS. l-7 or 8-11, but one in which the belt (lettered K) ismade of one continuous strip of flexible material having adjacent endsformed like the adjacent ends of the links in Said FIGS. I-Il. Thus inFIG. 12 these ends are joined by connectors 13 the same as'in FIGS. l-7which are fastened by means of fasteners 15 to the distal ends 9 offingers 5 at one end of the belt and to a distal end 11 of the tongue 7at the other end of the belt K. The action on a drum of this arrangementis similar to that already described in connection with any one of theconnectors 13 of FIGS. 1-7. The belt K has holes 35 in it correspondingto the holes 35 for registration with the dowel pins 33 on drum 1 ofFIGS. l-7. It is of course obvious that in any case such holes could beeliminated if the dowels33 were eliminated from the drum 1 fornonpositive driving operations. In such cases peripheral grooves on thedriving drum would be used to accommodate fastener heads such as 21. g

In FIG. 13 is shown a form of the invention in which the flexible beltis of one piece and endless. It is lettered T. Extending from itsopposite sides are L-shaped fingers 69 which interdigitate in adirection along the length of the belt and in its plane when flat. Thedistal ends 71 of these fingers are thus spaced from one another indirection along the belt length. Fasteners 15, like those of FIG. 3,attach the distal ends 71 to an appropriate rigid connector 75. Thus asthe portions of the belt under the connector 75 engage a circular drum,the distal ends 71 of the interdigitating fingers 69 lie in a commonplane which is substantially tangent to the drum surface.

From the above it will be apparent that in each form of the invention(FIGS. 1, 9, I2 and 13) there are adjacent flexible sheetlike portionssuch as M and N in the belt which are joined may lie anywhere in thespan D. In the FIG. 13 form the portions M and N are parts of oneundivided sheet; whereas corresponding portions in the forms of FIGS.1-12 are divided. In the forms of FIGS. 1-7, 12 and 13 the angular locusof the tangent plane may vary under any angular vibration of theconnector; whereas the FIGS. 8-11 form this is not the case, because thecircular grooves 63 and 67 positively determine the angular locus of theconnector and of the tangent plane.

It will be seen that in all forms of the invention the belt parts withthe exception of the connectors are ribbonlike and that their forms canbe conveniently made by shearing or the like. It will also be apparentthat weldments may be substituted for the screw fasteners and that thefollower rollers 55 and 57 may be omitted and nonrotary finger followersused. Holes such as 35 and pins such as 33 may be employed or omittedfrom any form of the invention. Also, other appropriate numbers ofinterdigitating fingers and tongues such as 9 and 11 may be employed.

In conclusion, certain of the basic features of the invention arepresented in exaggerated form in the skeleton diagram of FIG. 14. Thisshows a drum such as 1 or the like on which are wrapped adjacentportions such as M and N of flexible beltforrning material havinginterdigitated extensions 5 and 7, the distal ends 9 and 11 of which aremaintained in a common plane PP by a rigid connector 3 attached theretoat fasteners 15 and spaced apart the distance D. From the FIG. 15 it isclear that the connector 13 is normally resiliently held in the positionshown and that the material at locations of fasteners 15 is free of anybending. Under light weights of connectors l3 and their loads, thetangent point 0 normally takes up a position bisecting D but, as theconnector oscillates somewhat, this point 0 may deviate some from thebisecting position without arriving closely enough near either of thepoints of fastening 15 to result in any substantial bending stressesthereat. Under heavier weights of connectors 13 and their loads (as inFIGS. 8-10) the guides such as 63 and 67 prevent excessive oscillationsso that the position of O bisecting D is positively maintained.

In the link form of the invention (FIG. 1) in which the belt is composedpreferably of a number of precision die blanked links (holes included inthe blanking) it is important that the belt shall remain straight in thereaches between drums, which is to say that it shall not assume a cambertransverse to the belt center line CC. Such a camber may occur if theblanked pairs of holes in the links 3 and/or if jig-drilled holes in theconnectors 13 are not exactly collinear on the perpendicularlytransverse lines 17 and 19, as may occur even with precision blankingand jigging. Any resulting small repetitive errors in blanking and jigdrilling become cumulative on one side or the other of the belt to bringabout said camber. Upon assembly, this is avoided by turning over everyother one of commonly blanked links 3 oppositely with respect to thecenter line C C. Likewise any contribution to camber occurring becauseof repetitive jig drilling errors in the connectors 13, upon assembly iscorrected by turning over every other connector oppositely with respectto the center line CC. To this end opposite faces of all connectors 13are made plane and parallel as shown in FIGS. 1 and 2 so that in eitherposition they present like inner faces contacting the links and likeouter faces for fastening workpieces thereto.

In view of the above, it will be seen that the several objects of theinvention are achieved and other advantageous results attained.

As various changes could be made in the above constructions withoutdeparting from the scope of the invention, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

What is claimed is:

l. A belt drive mechanism comprising spaced sidewalls, a driving drumand an idler drum mounted for rotation between the walls, a flexiblebelt having at least one pair of adjacent flexible sheet portions, atleast one extension from each of said adjacent portions projectingoppositely to one another in the direction of the belt length tointerdigitate the extensions in a plane when the belt is flat thereby tospace the ends of the extensions in the direction of the belt length, atleast one rigid connector, rigid fastening means between said connectorand said ends of the extensions respectively, guide grooves on theinsides of said walls having straight portions between the drums andbranched circular outer and inner portions at the ends of the drums,transversely projecting leading and trailing follower members on theconnector extending into said grooves for joint movements in thestraight portion and for individual movements in the branched circularportions respectively, and means for guiding the leading follower meansinto the inner circular groove and for switching the trailing followermeans into the outer circular groove.

2. A belt drive mechanism according to claim 1 wherein said switchingmeans comprises a comparatively large depth of said straight groove andsaid circular outer branch portion and a smaller depth of said circularinner branch portion with the projections of the leading and trailingfollower members being comparatively short and long respectively, onlythe inner circular branched groove admitting the leading followermembers.

3. A flexible belt mechanism comprising,

a connected series of adjacent links, each link having at least oneextension from each end, each extension having a distal end region, theextensions on adjacent links projecting oppositely in a straightconfiguration of the belt, thereby to interdigitate such extensions andto space said distal end regions in the direction of the belt length,

each link, including its extensions and their distal end regions, beingflexible, integral and normally substantially flat,

a plurality of rigid connectors,

and rigid fastening means between each connector and the distal endregions of a pair of the interdigitated extensions,

whereby said connectors will maintain said distal end regionssubstantially in a tangent plane outside of and tangent to said beltwhen it is in an arcuate configuration, thereby to avoid bending of thedistal end portions at said fastenings,

a pair of drums supporting said connected series of links around thedrums with straight reaches of the links therebetween,

a sidewall adjacent each side of the series and adjacent each end of atleast one drum,

opposite and like grooves in said walls,

short leading and long trailing followers extending transversely fromeach link movable in said grooves,

each of said grooves having comparatively deep straight portions alongsaid reaches for receiving said short and long followers and having aninner shallow circular branch around each drum admitting short leadingfollowers but not long trailing followers, and having an outer deepcircular branch around each drum to admit a long trailing followerincapable of entering said inner circular branch,

whereby oscillations of said distal end regions with respect to saidtangent plane are prevented.

4. A belt drive mechanism comprising spaced side members, a driving drumand a second drum mounted for rotation between the members, a flexiblebelt having at least one pair of adjacent flexible sheet portions, atleast one extension from each of said adjacent portions projectingoppositely to one another in the direction of the belt length tointerdigitate the extensions in a plane when the belt is flat thereby tospace the ends of the extensions in the direction of the belt length, atleast one rigid connector, rigid fastening means between said connectorand said ends of the extensions respectively, guide grooves on theinsides of said side members having portions extending between the drumsand branched curved outer and inner portions at the ends of the drums,transversely projecting leading andtrailing follower members on theconnector extending into said grooves for joint movements in theportions of the grooves between the drums and for individual movementsin the branched curved portions respectively, and switching means fordirecting the leading follower means into the inner curved groove andfor directing the trailing follower means into the outer curved groove.

5. A belt drive according to claim 4 wherein said switching meanscomprises a comparatively large depth of the grooves between drums andsaid curved outer branch portion and a smaller depth of said curvedinner branch portion with the projections of the leading and trailingfollower members being comparatively short and long respectively, onlythe inner curved branched groove admitting the leading follower membersand only the outer curved branched groove admitting the trailingfollower means. i

6. A belt drive according to claim 5 wherein said portions of thegrooves between the drums are straight and said curved inner and outerbranch portions of the grooves are substantially circular.

7. A flexible belt mechanism comprising,

a connected series of adjacent links, each link having at least oneextension from each end, each extension having a distal end region, theextensions on adjacent links projecting oppositely in a straightconfiguration of the belt, thereby to interdigitate such extensions andto space said distal end regions in the direction of the belt length,

each link, including its extensions and their distal end regions, beingflexible, integral and normally substantially flat,

a plurality of rigid connectors,

and rigid fastening means between each connector and the distal endregions of a pair of the interdigitated extenstons,

whereby said connectors will maintain said distal end regionssubstantially in a tangent plane outside of and tangent to said beltwhen it is in an arcuate configuration, thereby to avoid bending of thedistal end portions at said fastenings, followers but not the longtrailing followers, and having an outer deep circular branch around eachdrum to admit a long trailing follower incapable of entering said innercircular branch,

whereby oscillations of said distal end regions with respect to saidtangent plane are prevented.

E22 3? TED STATES PATENT oTTTtE QETlFlfiA'lE @F @QQ'HN Patent No. 336,783 Dated January 25 1972 Invent0r(s) Duane w. Woltjen It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 2, line 55, "link 19." should read line 19. Column 8, line 16,cancel followers but not the long trailing followers,; Cancel lines17-19 and insert:

a pair of drums supporting said connected series of links around thedrums with straight reaches of the links therebetween,

a side member adjacent each side of the series and adjacent each end ofat least one drum,

opposite and like grooves in said side members,

comparatively short leading and long trailing followers extendingtransversely from each link movable in said grooves,

each of said grooves having comparatively deep straight portions alongsaid reaches for receiving said short and long followers and having aninner shallow circular branch around each drum admitting the shortleading followers but not the long trailing followers, and having anouter deep circular branch around each drum to admit a long trailingfollower incapable of entering said inner circular branch,

Signed and sealed this 26th day of September 1972.

(SEAL) Attest:

EDWARD TIQFLETCEERJRT, Attesting Officer ROBERT GOTI'SCHALK Commissionerof Patents

1. A belt drive mechanism comprising spaced sidewalls, a driving drumand an idler drum mounted for rotation between the walls, a flexiblebelt having at least one pair of adjacent flexible sheet portions, atleast one extension from each of said adjacent portions projectingoppositely to one another in the direction of the belt length tointerdigitate the extensions in a plane when the belt is flat thereby tospace the ends of the extensions in the direction of the belt length, atleast one rigid connector, rigid fastening means between said connectorand said ends of the extensions respectively, guide grooves on theinsides of said walls having straight portions between the drums andbranched circular outer and inner portions at the ends of the drums,transversely projecting leading and trailing follower members on theconnector extending into said grooves for joint movements in thestraight portion and for individual movements in the branched circularportions respectively, and means for guiding the leading follower meansinto the inner circular groove and for switching the trailing followermeans into the outer circular groove.
 2. A belt drive mechanismaccording to claim 1 wherein said switching means comprises acomparatively large depth of said straight groove and said circularouter branch portion and a smaller depth of said circular inner branchportion with the projections of the leading and trailing followermembers being comparatively short and long respectively, only the innercircular branched groove admitting the leading follower members.
 3. Aflexible belt mechanism comprising, a connected series of adjacentlinks, each link having at least one extension from each end, eachextension having a distal end region, the extensions on adjacent linksprojecting oppositely in a straight configuration of the belt, therebyto interdigitate such extensions and to space said distal end regions inthe direction of the belt length, each link, including its extensionsand their distal end regions, being flexible, integral and normallysubstantially flat, a plurality of rigid connectors, and rigid fasteningmeans between each connector and the distal end regions of a pair of theinterdigitated extensions, whereby said connectors will maintain saiddistal end regions substantially in a tangent plane outside of andtangent to said belt when it is in an arcuate configuration, thereby toavoid bending of the distal end portions at said fastenings, a pair ofdrums supporting said connected series of links around the drums withstraight reaches of the links therebetween, a sidewall adjacent eachside of the series and adjacent each end of at least one drum, oppositeand like grooves in said walls, short leading and long trailingfollowers extending transversely from each link movable in said grooves,each of said grooves having comparatively deep straight portions alongsaid reaches for receiving said short and long followers and having aninner shallow circular branch around each drum admitting short leadingfollowers but not long trailing followers, and having an outer deepcircular branch around each drum to admit a long trailing followerincapable of entering said inner circular branch, whereby oscillationsof said distal end regions with respect to said tangent plane areprevented.
 4. A belt drive mechanism comprising spaced side members, adriving drum and a second drum mounted for rotation between the members,a flexible belt having at least one pair of adjacent flexible sheetportions, at least one extension from each of said adjacent portionsprojecting oppositely to one another in the direction of the belt lengthto interdigitate the extensions in a plane when the belt is flat therebyto space the ends of the extensions in the direction of the belt length,at least one rigid connector, rigid fastening means between saidconnector and said ends of the extensions respectively, guide grooves onthe insides of said side members having portions extending between thedrums and branched curved outer and inner portions at the ends of thedrums, transversely projecting leading and trailing follower members onthe connector extending into said grooves for joint movements in theportions of the grooves between the drums and for individual movementsin the branched curved portions respectively, and switching means fordirecting the leading follower means into the inner curved groove andfor directing the trailing follower means into the outer curved groove.5. A belt drive according to claim 4 wherein said switching meanscomprises a comparatively large depth of the grooves between drums andsaid curved outer branch portion and a smaller depth of said curvedinner branch portion with the projections of the leading and trailingfollower members being comparatively short and long respectively, onlythe inner curved branched groove admitting the leading follower membersand only the outer curved branched groove admitting the trailingfollower means.
 6. A belt drive according to claim 5 wherein saidportions of the grooves between the drums are straight and said curvedinner and outer branch portions of the grooves are substantiallycircular.
 7. A flexible belt mechanism comprising, a connected series ofadjacent links, each link having at least one extension from each end,each extension having a distal end region, the extensions on adjacentlinks projecting oppositely in a straight configuration of the belt,thereby to interdigitate such extensions and to space said distal endregions in the direction of the belt length, each link, including itsextensions and their distal end regions, being flexible, integral andnormally substantially flat, a plurality of rigid connectors, and rigidfastening means between each connector and the distal end regions of apair Of the interdigitated extensions, whereby said connectors willmaintain said distal end regions substantially in a tangent planeoutside of and tangent to said belt when it is in an arcuateconfiguration, thereby to avoid bending of the distal end portions atsaid fastenings, a pair of drums supporting said connected series oflinks around the drums with straight reaches of the links therebetween,a side member adjacent each side of the series and adjacent each end ofat least one drum, opposite and like grooves in said side members,comparatively short leading and long trailing followers extendingtransversely from each link movable in said grooves, each of saidgrooves having comparatively deep straight portions along said reachesfor receiving said short and long followers and having an inner shallowcircular branch around each drum admitting the short leading followersbut not the long trailing followers, and having an outer deep circularbranch around each drum to admit a long trailing follower incapable ofentering said inner circular branch, whereby oscillations of said distalend regions with respect to said tangent plane are prevented.